This invention relates to packings for gas-liquid contact apparatus, and particularly pertains to the configurations of individual packing elements and beds formed of such elements.
The packing elements of the invention are used to form beds of dumped or randomly oriented packings. Such packings are well known in the art and are used for a wide variety of purposes in scrubbers, absorbers and distillation columns for various types of mass transfer apparatus. Typical existing packings in this category are Pall rings, Raschig rings, and packings sold under the trademarks Intalox saddles, metal Intalox and Cascade Mini-Rings. Packing elements which have some similarities to the packings of this invention are disclosed in U.S. Pat. Nos. 4,041,113, 4,303,599 and 4,333,892, the disclosures of which are incorporated herein by reference.
Beds of random dumped packing are normally formed by dumping large quantities of packing elements on a conventional support plate which is mounted in a tower or other vessel. One type of support plate is a perforated sheet which has a sinuous or corrugated configuration so that gas can enter the bed from the peaks of the support plate without opposition from a hydrostatic head which may exist in the valleys of the support plate. After being randomly dumped on the support plate, the packing elements may be slightly agitated or raked level with a small board or other tool. There is no piece-by-piece positioning or orientation of the elements.
The vessel is sealed. In operation, gas is introduced by a gas inlet in a lower part of the vessel, and the gas is exhausted or discharged from a gas outlet in the upper part of the vessel. As the gas moves from the inlet to the outlet, it passes upwardly through the support plate and through the randomly dumped bed. Simultaneously with the ascending flow of the gas, a body of liquid is moving downwardly through the bed of packing elements. The liquid is distributed on the upper surface of the bed by means of an orifice pan, weir channel or spray nozzle distributor as is well known in the art. As the liquid moves downwardly through the bed under the influence of gravitational forces, it wets the surfaces of the elements, forming a renewing film to promote the effective contact between the gas and the liquid. The liquid eventually passes through the support plate and then flows to a liquid outlet means.
A paramount objective of the invention is to provide a packing which results in a high efficiency without an excessive pressure drop. This high efficiency is believed to be attributable to the effective wetting of the available surface of the packing, improved liquid flow and distribution on and between the individual elements at various orientations thereof, reduced liquid dripping as it flows from the elements, and some lateral flow of the liquid as it moves from element-to-element. Another major object is to obtain relatively uniform contact throughout the bed so that the gas-liquid contact activity at the center of the bed is approximately the same as the activity in the side areas and elsewhere in the bed.
Other objects are to produce a relatively uniform bed structure because the elements will not have a preferential orientation when they are dumped into the bed, to provide packing elements which resist nesting, and to provide packing elements which have a high strength with respect to their size, weight and wall thickness. The latter feature makes it possible to form deeper beds of packing without deforming the lower elements in the bed, and to use thinner gauge materials in situations where beds are of normal depth.